I noticed at the start of it...the 5h7 runs on the A and the D back to the 7th fret on the A string (the E), are you fretting that E note with your middle finger? The same for the A (7th fret E string)...I trying to do with my ring finger, and it causes a lot of complications when I have to try and roll that ring finger back on a run to fret the note, is it easier to fret it with your middle finger (if that's what you are doing), and if that's not what you are doing, what should I do to practice the "rolling back"?

You absolutely right, I play it with my middle finger. It is more convenient this way. Be careful not to tilt your hand too much because you will get some pains over a long period (something similar happened to me). Try to stretch the middle as far as you can to grasp that note down and in the same time the hand as much straight as you can - while you practice it slow, and later on, after a few months when the exercise really embed itself in your memory, the muscles should stay relaxed enough and with a hand not too much tilted. This way the hand will tense up less.